#include <REGX52.H>

void Delay(unsigned int xms)	//@12.000MHz
{
	unsigned char data i, j;

	while(xms--)
	{
		i = 2;
		j = 239;
		do
		{
			while (--j);
		} while (--i);
	}
}

unsigned char LEDNum;
void main()
{
	P2_0 = 0;
	while(1)
	{
		if (P3_1 == 0) 
		{
			Delay(20);
			while (P3_1 == 0);
			Delay(20);
			
			LEDNum++;
			if (LEDNum >=8)
			{
				LEDNum = 0;
			}
			P2 = ~(0x01<<LEDNum);
		}
		if (P3_0 == 0) 
		{
			Delay(20);
			while (P3_0 == 0);
			Delay(20);
			
			if (LEDNum == 0)
			{
				LEDNum = 7;
			}
			else 
			{
				LEDNum--;
			}
			P2 = ~(0x01<<LEDNum);
		}
	}
}

